1. Field of the invention
The present invention relates in general to drilling apparatus for boring a hole into the earth, and more particularly to an apparatus for handling and storing drill pipe sections used in drilling operations.
2. Description of the prior art
Various drill pipe carousel/magazine devices are in general use today with a drilling rig for handling and storing sections of drill pipe. Drilling rigs of this type typically have an upright mast with a drill table or floor at the lower end thereof and a rotary drive mechanism or rotary head mounted on the mast for linear movement therealong as the drill string is drilled into the earth in a generally vertical direction. In conventional blasthole drillings, usually only shallow holes are necessary; therefore, one thirty to fifty-five foot section of drill pipe remains attached to the rotary head with a drill bit attached to the lower end thereof. As the drill pipe is rotated, a downward force is applied by the rotary head, causing the drill bit to bore the hole in the earth. When the drill bit has reached the required depth, it is retracted up into the mast, and the portable drilling rig is relocated to the next location where a blasthole is to be drilled.
When it becomes necessary to drill holes deeper than the single pass capability of the drill, (i.e., the length of a single drill pipe section), a plurality of drill pipe sections are attached end to end, forming a drill string for boring this deeper hole. In this instance, the initial drilling section must be released from the rotary head and subsequent drill pipe sections connected therebetween. Conventionally, these subsequent drill pipe sections are carried by a "Lazy Susan" type drill pipe carousel or magazine which is housed within the mast. The carousel rotates about an axis parallel to that of the drill hole in the earth and positions these drill pipe sections in line with center line of the drill hole. A typical drill pipe carousel has a plurality of sockets at the lower end thereof, each for retaining the lower end of a drill pipe section, and a generally elongated or oval slot in a plate at the upper end thereof for receiving a reduced top section of the drill pipe. The drill pipe has opposite flat surfaces for engaging the slot. Once engaged, the drill pipe is then rotated slightly to engage a locking mechanism for retaining the top section of the drill pipe therein.
The drill pipe carousel is pivotally connected to the mast so that it, as a unit, may pivot outwardly from a stored position to an operating position where one of the drill pipe sections is in line with the rotary head and drill hole. In this operating position, the rotary head is lowered to attach the rotary driving spindle to the male threads at the top of the drill pipe. With this connection made, the rotary head is raised, removing the lower section of the drill pipe from its retaining receptacle, or socket. Next, the carousel is pivoted back into the mast, out of the way, so that the rotary head may be lowered and the lower end of the drill pipe section connected to the upper end of the drill pipe section already in the hole. After drilling a depth equal to the length of the drill pipe section, the top of the section of drill pipe remaining in the hole is clamped to prevent it from rotating, the rotary head spindle is unscrewed from the drill string and the rotary head raised to the top of the mast so that the carousel may again be pivoted into place, aligning a subsequent section of drill pipe with the rotary head and drill hole, after which the process repeats itself as described hereinabove.
When removing the drill string from the drill hole, the above procedure is reversed. Specifically, the rotary head with the drill string attached is raised so that a length of drill pipe section is removed from the drill hole. In this position, the top of the section of drill pipe remaining in the hole is clamped to prevent it from falling back into the hole and also to prevent it from rotating as the top, just withdrawn section of drill pipe is unscrewed therefrom. After this top section of drill pipe is unscrewed from the drill string, the rotary head is further raised and the drill pipe carousel pivoted into place so that the drill pipe socket at the lower end thereof is in alignment with the drill pipe section and the drill hole. The rotary head is then lowered so that the drill pipe section is inserted into the socket, and the top of the drill pipe section "keyed" into the elongated slot in the upper retaining plate thereof. Slight further counterclockwise rotation of the drill pipe will lock it into place within the carousel. Further counterclockwise rotation will unscrew the rotary head spindle from the drill pipe section, which permits the carousel to be pivoted back out of the way so that the rotary head may again be lowered and the spindle attached to the section of drill pipe within the hole, and the process repeated as set out hereinabove.
When drilling directionally, i.e., nonvertical holes, an additional device is required to retain the drill pipe section in alignment with the drill hole as the pipe section is being attached to or removed from the drill string in the hole, as this "free" end of the drill pipe section connected to the rotary head will fall under its own weight when disconnected from the drill string or when the carousel is pivoted back into the mast out of the way of the rotary head. When directional drilling, the additional step of positioning this drill pipe retaining device at the bottom of the mast must be included to retain the drill pipe section in alignment with the drill hole, and must be removed once this connection is made so that it will not interfere with the rotary head as drilling proceeds.
These conventional devices are inefficient in that additional steps, made unnecessary by the present invention, are required to perform the drilling operation. Specifically, after the connection is made between the drill pipe and the rotary head, the rotary head must be raised to withdraw the drill pipe from its retaining socket in the lower portion of the carousel, after which the carousel must be pivoted back out of the way in order not to interfere with the downward motion of the rotary head. Likewise, when removing the drill pipe from the drill string, the rotary head must be raised sufficiently to permit the bottom of the drill pipe section to clear the drill pipe socket in the carousel, but not raised so much that the "flat" sections at the top of the drill pipe are above the carousel top retaining plate. The drill pipe section must be incrementally rotated so that the flat sections thereof are in alignment with the elongate slot in the drill pipe carousel upper retaining plate. After this alignment is made, the carousel may be pivoted into place and the rotary head lowered, lowering the bottom section of the drill pipe into the carousel pipe retaining socket. This is a very tedious and time consuming operation.